Data processing systems, such as personal computers, tablet computers, entertainment systems, game consoles, and cellular telephones, commonly include keyboards that use keys or mechanical trackballs for cursor navigation. Existing mechanical trackballs are prone to failure due to mechanical wear and malfunction due to environmental contaminants, such as dust and lint. Moreover, functional tracking performance of mechanical trackballs is not as good as that for purely optical devices. Jog keys typically only permit incremental up/down and left/right cursor movements. In addition, mechanical trackballs have large form factors, requiring significant portion of the keyboard surface, and keys require a much larger area underneath the keyboard making them unsuitable for many applications.